ES doesn't update from MySql

Hi everyone,
I've a MySql database with 17727677 rows. I've created a jdbc river to connect it to ElasticSearch cluster composed by 11 nodes (1 master and 10 slaves). This is my river.

curl -XGET 'http://localhost:9200/_river/airplanethreey/_meta'
{"_index":"_river","_type":"airplanethreey","_id":"_meta","_version":1,"exists":true, "_source" : {
"type" : "jdbc",
"jdbc" : {
"driver" : "com.mysql.jdbc.Driver",
"url" : "jdbc:mysql://localhost:3306/airplanethreey",
"user" : "root",
"password" : "pass",
"sql" : "SELECT ID as _id, and the other fields",
"poll" : "1m",
"strategy" : "simple",
"autocommit" : "true"
"index" : {
"index" : "airplanethreey",
"type" : "flight"

With a smaller dataset it works and there is the update in ElasticSearch, with the big one no: in the terminal of master node of ES there is "always" this situation : the computing never ends
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